I've been testing this deck for a while, and I'm amazed at how solid a deck it is in an HGSS-on format. With Kingdra as a partner, it addresses all of Cinccino's biggest problems; hitting the higher numbers, surviving attacks, and, most importantly, the Donphan matchup.
First, you should know that both Kingdra and Cinccino have strong attacks with low energy cost, with Cinccino requiring a DCE, and Kingdra needs a sole water energy. The duo is very fast, and can be all set up Turn 2 (due to the Rare Candy nerf)
Secondly, Kingdra is an absolute blessing in the Donphan matchup. For Cinccino alone, Donphan is a nightmare of a matchup, I bet it is unwinnable. But, unless Donphan pulls out a PlusPower (no Expert Belt in HGSS on), Kingdra is never 2HKOed. In return, if you have 2 Kingdra's on the bench, Kingdra can OHKO Donphan with its attack after two Spray Splashs.
Finally, Kingdra's Spray Splash also helps Cinccino out in other matchups, like with Reshiram, Zekrom, and (somewhat) Gengar. If you have 2 Kingdras benched, and a PlusPower, Reshiram and Zekrom are defeated by a single "Do the Wave". Gengar is a little tricky, but that is why I run Ruins of Alph (a Stadium which negates Resistance)
Yes, there may be a few ifs, and, reality is, you won't get the perfect set up 100% of the time. But if there is anyone out there that is running Cinccino, try running Kingdra along with it. I guarantee that you won't be disappointed with the results.